A note on hermite-fejér interpolation for the unit circle

AbstractIn this note, an extension to the unit circle of the classical Hermite-Fejér Theorem is given

Travel time stability in weakly range-dependent sound channels

Travel time stability is investigated in environments consisting of a range-independent background sound-speed profile on which a highly structured range-dependent perturbation is superimposed. The stability of both unconstrained and constrained (eigenray) travel times are considered. Both general theoretical arguments and analytical estimates of time spreads suggest that travel time stability is largely controlled by a property $\omega ^{\prime}$ of the background sound speed profile. Here, $2\pi/\omega (I)$ is the range of a ray double loop and $I$ is the ray action variable. Numerical results for both volume scattering by internal waves in deep ocean environments and rough surface scattering in upward refracting environments are shown to confirm the expectation that travel time stability is largely controlled by $\omega ^{\prime}$.Comment: Submitted to J. Acoust. Soc. Am., 30 June 200

Decoupled and unidirectional asymptotic models for the propagation of internal waves

We study the relevance of various scalar equations, such as inviscid Burgers', Korteweg-de Vries (KdV), extended KdV, and higher order equations (of Camassa-Holm type), as asymptotic models for the propagation of internal waves in a two-fluid system. These scalar evolution equations may be justified with two approaches. The first method consists in approximating the flow with two decoupled, counterpropagating waves, each one satisfying such an equation. One also recovers homologous equations when focusing on a given direction of propagation, and seeking unidirectional approximate solutions. This second justification is more restrictive as for the admissible initial data, but yields greater accuracy. Additionally, we present several new coupled asymptotic models: a Green-Naghdi type model, its simplified version in the so-called Camassa-Holm regime, and a weakly decoupled model. All of the models are rigorously justified in the sense of consistency

EXCITATION of COUPLED STELLAR MOTIONS in the GALACTIC DISK by ORBITING SATELLITES

We use a set of high-resolution N-body simulations of the Galactic disk to study its interactions with the population of cosmologically predicted satellites. One simulation illustrates that multiple passages of massive satellites with different velocities through the disk generate a wobble, which has the appearance of rings in face-on projections of the stellar disk. They also produce flares in the outer disk parts and gradually heat the disk through bending waves. A different numerical experiment shows that an individual satellite as massive as the Sagittarius dwarf galaxy passing through the disk will drive coupled horizontal and vertical oscillations of stars in underdense regions with small associated heating. This experiment shows that vertical excursions of stars in these low-density regions can exceed 1 kpc in the Solar neighborhood, resembling the recently locally detected coherent vertical oscillations. They can also induce non-zero vertical streaming motions as large as 10-20 km s-1, which is consistent with recent observations in the Galactic disk. This phenomenon appears as a local ring with modest associated disk heating. © 2016. The American Astronomical Society. All rights reserved

On global models for isolated rotating axisymmetric charged bodies; uniqueness of the exterior field

A relatively recent study by Mars and Senovilla provided us with a uniqueness result for the exterior vacuum gravitational field generated by an isolated distribution of matter in axial rotation in equilibrium in General Relativity. The generalisation to exterior electrovacuum gravitational fields, to include charged rotating objects, is presented here.Comment: LaTeX, 21 pages, uses iopart styl

Transition paths of marine debris and the stability of the garbage patches

We used transition path theory (TPT) to infer "reactive" pathways of floating marine debris trajectories. The TPT analysis was applied on a pollution-aware time-homogeneous Markov chain model constructed from trajectories produced by satellite-tracked undrogued buoys from the NOAA Global Drifter Program. The latter involved coping with the openness of the system in physical space, which further required an adaptation of the standard TPT setting. Directly connecting pollution sources along coastlines with garbage patches of varied strengths, the unveiled reactive pollution routes represent alternative targets for ocean cleanup efforts. Among our specific findings we highlight: constraining a highly probable pollution source for the Great Pacific Garbage Patch; characterizing the weakness of the Indian Ocean gyre as a trap for plastic waste; and unveiling a tendency of the subtropical gyres to export garbage toward the coastlines rather than to other gyres in the event of anomalously intense winds.Comment: Submitted to Chao

Applicability of SERVQUAL in restaurants: an exploratory study in a Portuguese resort

SERVQUAL is the most popular instrument to ascertain service quality. However, some debate exists about its ability to characterize different service environments. Furthermore, there is not a consensus about the inclusion of customer expectations in the model. The research presented in this paper intends to discuss the applicability of SERVQUAL to restaurant services and to analyze the inclusion of customer expectations in such environment. The research was developed in a Portuguese resort and more than 300 customers, from two different restaurants, were invited to participate in the study

Tourist spaces and tourism policy in Spain and Portugal

Advances in Cultura, Tourism and Hospitality Research;10, 235-249This study analyses the relationship between the development of the tourism policy of Spain and Portugal and their effects on regional imbalances. Despite the proximity of the two countries and their specialisation in tourism, there are few comparative studies on tourism of the two Iberian countries. The study focuses on the two major phases of tourism policy: the period of mass tourism and post-Fordist stage. In the conclusions we refer the debate on the existence of a model of development based on tourism to the Latin countries of Southern Europe and we note the export process of the Spanish low-cost tourism model to other countries.Financiado por el Gobierno de España, Programa Fundamental de Investigación, Proyecto de I+D (CSO2012-30840) "Geografías de la crisis: análisis de los territorios urbanos y turísticos de las Islas Baleares, Costa del Sol y principales destinos del Caribe y América Central"